Unifi wireless network overloaded? Or something.....

[TrevorHall]

Good afternoon

 

I have a unifi wireless network consisting of 28 AP's a mix of AP-AC and AP-AC-Pro. I have a separate SSID setup for chromebooks. 2g is set to HT20 5g set to VHT40 channels and power all set to auto. On the pro versions I have band steering enabled set to Prefer 5g. Controller version 5.5.24

 

Ok so here's what happens. The wifi has been fine all morning, had a couple of locations with 28 - 33 devices per AP no problem at all. Then sudden in the last hour no one can log on a chromebook, you type your username in but it does not take you to the password screen, no error, nothing. If I leave it several minutes it reports the wifi connection is not available then connects to the chromebook SSID but still will not allow a logon.

 

Ok so first thought was loading? Checked the AP 40% channel utilisation on N/B/G and 13% on N/A/AC. This is higher than normal, but should not cause a total outage.

Ok second thought, DHCP/DNS issue? Checked. DCHP had a couple of BAD_ADDRESSES these seem to be because of chromebooks. But only had 6 of those so should of only affected 6 - 12 devices. DCHP and DNS logs are totally clear, no issues.

Ok third thought, internet connection is overloaded. We have a 300/1000 line. It was using 30mbit down, tons of capacity left

Ok fourth thought, the internet filter, an ageing Dell Sonicwall, maybe that could not handle all the requests? checked the load 31% cpu load. Checked a wired pc, full speed internet, speedtest result 266 down 299 up.

 

Its not just chromebooks. Wireless laptops, iphone can not connect either. If I move away from the affected room to connect to another AP I do then connect.

 

Does anyone have any idea's? Something I should look at? This has been on going for a week and is stressing me out. The data says there is no problem, but there is!

[DalekSec]

Stupid question, have you restarted said AP? If you've just done it in the console it's worth unplugging it completely. I've had likewise problems in the past and at home (have unifi at home) and have been solved by unplugged the PoE, and if that doesn't work change the AP and see if it's still a problem?

[TrevorHall]

Hi

 

Thanks for replying

 

Yes the AP has been restarted a few times this week. I am going to check the switch powering it to see if its reporting any issues. My brain is saying maybe it is not running on a true 1gb full duplex line. It is powered by a ubiquti tough switch which I am not at all impressed by! Also I just moved the mouse over the channel bar to see its reporting Tx Retry 82.9% dropped

[DalekSec]

It could be a faulty AP? Have you place another one in the same place to see if it still does it?

[TrevorHall]

I was thinking that, however I have just checked the other 19 Pro ap's and all report between 70 and 99% Tx Dropped. That can not be right. 99% loss on some ap's

[DalekSec]

I'm trying to think what it could be, definitely shouldn't be that high on Tx Dropped. I don't have a UniFi system i can access at the moment to have a look at. Will have a look at my home rig when i get the chance to compare Tx rates.

[chazzy2501]

it could be interference from a non-wifi device. security camera, dect phone, microwave, etc. Have you tried manually changing (forcing the wifi channel on the 2.4Ghz) Try ch1 then ch11. Unless you have a spectrum analyser. (I do!) Every now and again our science dept, turn on their birdbox and the 6th form can't use facebook! Can't be helped!

 

EDIT: I see you set prefer 5Ghz but that 2.4 will always be stronger (regardless if it's trash) and some devices will still hop onto 2.4 then switch.

 

EDIT2: I've also been very harsh and only allow clients to connect if they can't at least get 18Mbps connection. In the Wireless settings you can enforce 2g Data rate control. This stops weak clients who are too far away from diminishing the throughput.

Edited April 25, 2018 by chazzy2501

[chazzy2501]

I've re-read your post and I see you have the ap-ac we have found that many of them are running very hot and sometimes fail to pass traffic even though they allow clients to connect. We've put holes in our ceiling tiles to allow air flow and on others just reduced their wi-fi power settings. next time its failing check how hot the back is.. on one of ours it was uncomfortable to hold!